NSF Nugget for FY06 Improving the New Superconductor MgB 2 Sept FRG on Two Gap Superconductivity Wisconsin-Penn State- Arizona State-Puerto Rico- Mayaguez collaboration DMR PI David Larbalestier, Eric Hellstrom and Paul Voyles (UW), Zi-Kui Liu (Penn State), Nate Newman and John Rowell (Arizona State), and Oswald Uwakweh (U. Puerto Rico Mayaguez)

Improving the New Superconductor MgB 2 Work in groups of Eric Hellstrom and David Larbalestier (UW), in collaboration with Oswald Uwakweh, UPRM, DMR Above: Scanning electron image of MgB 2 grains. Grains in the enlarged portion are only ~30 nm is size Right: Transmission electron image of an MgB 2 grain showing beneficial lattice dislocations (TEM in Paul Voyles group). The new superconductor MgB 2 promises advances in magnet technology for MRI, fusion energy, and particle accelerators, and in aerospace applications. To achieve that promise, the electric current carrying capacity (J c ) in a magnetic field of MgB 2 must be improved. J c can be increased by creating MgB 2 with a smaller grain size, more crystal lattice defects, alloying with elements like carbon, and grains that are well connected to each other with no second phases blocking the flow of the supercurrent. We have pioneered mechanical alloying of carbon into MgB 2. This process has given us record high J c under applied fields (8x10 4 A/cm 2 at 8T 4.2K) for bulk MgB 2. Our method simultaneously refines grains, generates intragranular defects, and alloys C into the MgB 2. We have also developed a method to purify the B powder used to make MgB 2. Purified B results in MgB 2 with cleaner grain boundaries, increasing the current carrying fraction of the sample by a factor of up to nm high density of defects inside an MgB 2 grain

Education: One graduate (Ben Senkowicz), three undergraduates (Jason Mantei, Richard Mungall, Jonathan Hedstrom), one young sabbatical visiting scientist (Akiyoshi Matsumoto of NIMS Japan), worked on bulk MgB 2 research supported by this NSF Award. Close collaboration with P. Voyles graduate student, Ye Zhu, is also occurring. Camp Badger – Ben Senkowicz led Camp Badger demos and Mantei did ESTEAM demos (ESTEAM is a Saturday activity in fall semester where high school students with high SAT score who are interested in engineering are invited on campus to show them what is available in engineering.) Societal Impact: The ability to transport electric current without dissipating electricity as heat is of paramount importance for electrical transport and electro- magnet technologies. This work could enable a new generation of magnets for MRI, fusion energy, and particle accelerators. Support of the PREM at UPRM – we are collaborating with UPRM on alloying of MgB2 – UPRM needed a glove box to be able to mill MgB2 without contamination. Uwakweh’s student Richard Perez came to Madison to work in our glove box, packed up a spare and shipped it to UPRM where it is now installed. Our first joint paper on the effect of milling atmosphere has just appeared. Improving the New Superconductor MgB 2 Work in groups of Eric Hellstrom and David Larbalestier (UW), in collaboration with Oswald Uwakweh, UPRM, DMR